The present disclosure relates generally to marine systems and, more particularly, to marine devices determining a boundary defining region of interest around the perimeter of, adjacent to the perimeter of or within a body of water. In the context of marine devices, a contour map may include contour lines that indicate a depth of underwater terrain within a body of water at a plurality of geolocations within the shoreline of the body of water. Similar to other types of cartography, each marine contour line may represent geographic locations having similar depth. For example, adjacent contour lines in close proximity (reduced separation of contour lines) represent a larger change in depth than adjacent contour lines spaced further apart (increased separation of contour lines). Thus, just as topographic maps above sea level indicate various elevations due to valleys, ridges, hills, etc., marine contour lines may represent the topography at the bottom of a body of water, such as a seabed, lakebed, riverbed, etc.
As shown in FIG. 1A, a traditional marine device, such as marine navigation devices 101 in environment 100, may acquire depth data using sensor devices, such as sonar transducers, and use the depth data to calculate contour lines for an area within a body of water 195 having a natural shoreline 140. As a map is generated for the body of water, these calculated contour lines may be included in (overlaid onto) the map to provide information relating to the topography at the bottom of a body of water. However, as shown in FIGS. 1B-1C, calculated depth data may be applied to geographic locations within an expanded area 112. Specifically, depth data and contour line data may be calculated for geographic areas that extend beyond geographic locations navigated by a boat 190 equipped with the conventional marine navigation device 101. As a result, the use of an expanded area 112 may result in contour line data being determined for above-water terrain along a natural shoreline 140 of a body of water 195 as boat 190 is navigated along the perimeter of body of water 195. Although the depth of an area within the perimeter of the body of water 195 may be accurately determined (e.g., a depth of 10 feet, 15 feet, etc.), conventional marine devices may estimate depths and contour lines for above-water level terrain within an expanded area 112 adjacent to the current location of boat 190. For instance, a determined depth in an area along the perimeter of a body of water 195 may be associated with the beach, coast, or any land that is not part of the body of water. The extent to which the above-water level terrain is associated with estimated depths and contour lines for areas within body of water 195 may be determined by the size of expanded area 112.
Traditional marine devices do not enable a user to define or otherwise identify a shoreline 140 of a body of water or an area of interest within the body of water. Some conventional marine navigation devices 101 may store a map of one or more bodies of water in memory and present the stored map in addition to contour lines determined by the conventional marine navigation device 101. Such conventional marine navigation devices 101 do not determine a shoreline 140 depicted in the map of a body of water 195 (e.g., geographic locations associated with the shoreline of body of water 195) and, thus, do not utilize the shoreline 140 to determine a region of interest enclosed by a boundary.
As a result, traditional marine devices may allow for the collection and viewing of marine contour line data, but have several drawbacks or limitations.